Microfluidic PCR System Using Silicone Oil Carrier Fluid
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Solution Overview
Problem
Current analysis systems for detecting rare mutated cells in bodily fluids face challenges in effective amplification and contamination risks due to sample contact with solid surfaces during thermal cycling in PCR processes.
Innovation Solution
A microfluidic analysis system using a biologically non-reactive silicone oil as a carrier fluid to envelop samples, preventing surface contact and employing a centrifuge with opposed carrier fluid channels for separation and thermal cycling stages with controlled temperature ramping, allowing for efficient PCR amplification without contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal cycling is performed in conventional PCR systems with solid surfaces, then amplification can be achieved, but sample contamination occurs due to contact with surfaces in temperature zones and channels
Solution Approach 1:
The patent employs a liquid carrier fluid system to replace solid surfaces for sample containment during thermal cycling. The sample is suspended in a carrier fluid that flows through the temperature zones, eliminating contact between the sample and solid channel walls. This hydraulic approach prevents contamination while maintaining the thermal cycling function.
Solution Approach 2:
The carrier fluid acts as an intermediary between the sample and the solid surfaces of the microfluidic device. It mediates the thermal energy transfer from the solid walls to the sample while preventing direct contact between the sample and potentially contaminating surfaces. The carrier fluid thus serves as a protective barrier that enables heat transfer without contamination.
2Measurement precision
If rare mutated cells are detected in bodily fluids, then early cancer diagnosis is enabled, but the target cells are very rare requiring very effective amplification
Solution Approach 1:
The patent segments the PCR process into distinct functional zones within the microfluidic device: a mixing zone for sample preparation, thermal cycling zones for amplification, and detection zones for analysis. This segmentation allows each stage to be optimized independently, ensuring both high detection sensitivity for rare cells and efficient amplification through controlled fluid flow and temperature gradients.
Solution Approach 2:
The system dynamically changes temperature parameters across different zones and time periods to optimize both detection sensitivity and amplification efficiency. Rapid thermal cycling with precise temperature control enables efficient DNA amplification while the controlled flow rates and temperature gradients enhance the detection sensitivity for rare mutated cells in the original sample.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves effective amplification and detection of rare cells with reduced contamination risk, enabling early cancer diagnosis and high-throughput processing with modular, reliable, and cost-effective design.
Implementation Method 1
a centrifuge for separation of samples from an input fluid and for introduction of the samples to the primary carrier fluid
Implementation Method 2
a channel heats, and then cools PCR reactants cyclically
Data Source
AI summary
A microfluidic analysis system (1) performs polymerase chain reaction (PCR) analysis on a bio sample. In a centrifuge (6) the sample is separated into DNA and RNA constituents. The vortex is created by opposing flow of a silicon oil primary carrier fluid effecting circulation by viscous drag. The bio sample exits the centrifuge enveloped in the primary carrier fluid. This is pumped by a flow controller (7) to a thermal stage (9). The thermal stage (9) has a number of microfluidic devices (70) each having thermal zones (71, 72, 73) in which the bio sample is heated or cooled by heat conduction to/from a thermal carrier fluid and the primary carrier fluid. Thus, the carrier fluids envelope the sample, control its flowrate, and control its temperature without need for moving parts at the micro scale.